The present invention relates to a method and apparatus for monitoring the supply of cap members, for example crown corks, roll-on caps, or similar caps, from a magazine or supply bin, via a channel, to the capping mechanism of a capping machine, whereby at least one signal emitter, which is provided at said channel, generates an emitted signal that changes as the cap members move past, with a disruption signal being derived from the emitted signal if this emitted signal does not change during a specified time interval.
With capping machines for bottles or similar vessels, the members used for capping are generally supplied from a magazine or supply bin, via a channel, to the capping mechanism of the machine. In so doing, interruptions in the orderly supply of the cap members cannot always be prevented, for example if the cap members become jammed in the channel that serves for the supply or in the capping mechanism, if gap bridging of the cap members occurs in the supply bin, or, where the supply bin is not timely refilled, no cap elements, or only an insufficient number of such elements, pass from the supply bin into the channel that serves for the supply of these cap members. In order to prevent disruption of operation by having uncapped bottles or similar vessels leaving the capping machine, it is necessary to continuously monitor the orderly supply of the cap members to the capping mechanism.
To accomplish this monitoring, it was proposed in German Gebrauchsmuster No. 19 60 680 to provide an electrical signal emitter that generates a emitted signal on the channel that serves for the supply of the capping members. This emitted signal always has a first state when a cap member is located in the effective range of the signal emitter, and has a second state when no cap member is in the effective range of the signal emitter or if a gap exists between two cap members that directly follow one another in the channel and have their peripheries (for example crown edges) resting against one another. Using a timing or delay element, a disruption signal is then generated from this emitted signal in an electrical control device if, after a change of the emitted signal occurs within a time interval that is fixed by the timing or delay element, a renewed change of the emitted signal does not take place.
This heretofore known method and apparatus have the drawback that due to the time interval that is fixed by the timing or delay element, a reliable monitoring is possible only within an output range of the capping machine that corresponds to this time interval. In other words, if the output rate of the machine is considerably less, it is possible for a disruption signal to be released even though an orderly supply of cap members is taking place. On the other hand, if disruptions occur when the machine is operating at considerably higher output rates, the release of the disruption signal is significantly delayed, i.e. is effected only after several working or machine cycles after a large number of uncapped bottles are in the capping machine or have left the machine.
It is therefore an object of the present invention to provide a method and apparatus for monitoring the supply of cap members, with this method and apparatus avoiding the drawbacks of the heretofore known method and apparatus and assuring a reliable monitoring independent of the respective output rate of a given capping machine